Lost Stars
by bravevulnerability
Summary: 'Three years ago, he had gone searching for a story, and he had found one in her. One he wanted to be a part of.' AU.
**A/N: Inspired by a prompt found on the castlefanficprompts page on tumblr.**

 **Slight trigger warning for brief mentions of mental illness.**

* * *

 _"Turn the page,_

 _Maybe we'll find a brand new ending..."_

-Lost Stars, Adam Levine

* * *

Castle sets her coffee on her desk, devoid of caffeine but sprinkled with a hint of cinnamon, and Kate glances up from her paperwork to smile at him, accepting her favorite blue mug with a murmur of thanks.

"How did movie night with Alexis go?" she inquires, scribbling her name at the bottom of the form and he grins back at her, like he always does when she remembers to ask about his daughter.

Alexis and Kate had met a few times and he knew his daughter liked the woman sitting across the desk from him, but her wariness was stronger, her disappointment and disapproval in this dysfunctional relationship they shared bleeding through every conversation lately.

"Dad, I know you care about her, that you may even… but I just don't think it's smart to-"

"Alexis, _please_ ," he always replies, unable to take it, not from her too. Enough people had told him to walk away, to let her go already, but over the last three years, he's managed to fall in love with Kate Beckett, and he won't add to the long list of people who have let her down, who have left her alone.

"Went well. Wish you could have been there," he answers honestly, watching her break away from the files in front of her to hum contently around the rim of her cup.

She looks pretty today, he notes, healthy. Her hair is falling in loose waves around her face, her skin retaining color, as if she's been spending more time in the sun instead of remaining cooped up inside, harboring the ghostly pallor that had consumed her cheeks. Cheeks that brighten with the gentlest hint of pink when she looks up at him.

"Me too," she murmurs, meeting his eyes with soft flecks of gold shimmering in hers. So clear, so with him in this moment. "Maybe next time? This latest case kept me busy all day yesterday."

"Oh? I wasn't able to make it for this one, was I?"

"Mm, no. Murder of an infamous gossip columnist."

Castle groans. "That totally sounds like a Beckett-flavored case and I missed it?"

"It was unfortunately lacking your insightful CIA theories," she nods, twirling the pen in her fingers, hiding her smile behind the fall of her hair.

"Sooner or later, one of my theories is going to prove true," Castle tells her, eliciting a familiar eye roll.

"I look forward to the day."

Rick grins, inches his fingers across the surface of her desk, tentatively cradling her hand in his embrace, smoothing his thumb along the bumps of her knuckles when she doesn't pull away. "So no murders today?"

"Not yet," she murmurs, trapping his thumb beneath hers, the curve of her lips slipping into something tender, adoring. "Don't jinx it, Castle."

"Even so, Ryan and Esposito could always handle it. If it's a simple case, that is."

"They're more than capable," she concedes, flicking her eyes to him with her curiosity ablaze. "Why?"

"I was thinking, maybe tonight, we could have a movie night of our own? Popcorn and M&Ms, some hot chocolate, and I promise, you can pick the film."

Kate hesitates, but lowers her coffee to the table, cups his hand in both of hers. "Like a date?"

"Why, Katherine Beckett, do you _want_ it to be a date?" he gasps, wiggling his fingers within the cage of hers, drawing out a soft chuckle.

"Actually, I'd love that," she whispers, tracing the heartlines running through his palm. "When did you want to-"

"Ms. Beckett?"

Castle stiffens as Patricia approaches, notices Kate's brow beginning to furrow at the approaching woman, a woman she sees everyday but still registers as a stranger. A woman who doesn't fit into this world.

"Yes?"

"Time for your vitamins, honey."

Oh no. No, no, she was doing so well today-

"Did you do this?" Kate asks with a frown, turning to him with confusion swirling in her eyes when the woman holds out the tiny plastic cup of vitamins Kate takes every day. Usually, it is either him or the head nurse, Lanie, that bring them to her, works them into the ruse, but he'd been late to arrive this morning, traffic slowing him down, and they must have assigned Kate's dosages to someone else for the day.

"I - yeah, I thought some vitamins would be good for you. You know, since you're always working so hard," Castle attempts to play along, incorporate the unexpected occurrence into the story. "Even the most badass detective in the city has to stay healthy."

But Kate isn't buying it, even the smallest unexplained shift threatening to shatter the fragile makings of her world.

"No, this isn't right," she mumbles and Castle rises from his chair across from her, takes the vitamins from Patricia with a tight smile and politely gestures to the door. The woman glances to Kate, an apologetic flash rippling through her eyes once she realizes what she's set in motion, but Rick shakes his head, not her fault, and turns his back on the woman to focus his full attention on Kate. "Where is - no, the precinct, this isn't-"

"Kate," he begins softly, but her hands are shaking, the pen clattering to the table, the panic beginning to consume her eyes, shrouding the traces of gold in horror. "Kate, you're okay."

Her eyes blindly search the room, the interior of a police station giving way to pastel colored walls and empty tables, the papers in front of her blank save for the signature of her name, and she rears back in her seat. Rick catches her before she can stumble from the chair.

"No," she chokes, the swelling start of a panic attack building within the confines of her chest, constricting her throat. "No, Rick, take me back-"

Castle eases around to kneel in front of her, cradling her face in his hands to gain her attention, to calm her before the storm can decimate her. It's been two weeks, a new record for her, since her last panic attack, and Burke had lowered her medication dosages at the sign of progress. Rick didn't want that progress to be overlooked, to be swept away, and he could bring her back, steady her before the anxiety bloomed into full-blown hysteria.

He refused to let them tie her down again.

"Breathe, Kate. Just breathe. I'm right here, always here."

The tears leak from her eyes, the ruins of the world they created together for her falling to pieces, leaving her crushed and battered by the devastation. Just like it did every time.

Three years ago, he had been an author seeking authenticity, shadowing a psychologist and meeting one of his most 'intriguing' patients, Katherine Beckett. He had been informed that Kate's mother had been murdered nearly 11 years ago, stabbed to death in an alley, and while it had sent her father into a spiral of alcoholism he would never emerge from, it had shut Kate down completely. Suffering a psychological break that had landed her in a psychiatric hospital for the last decade, the younger Beckett had coped by creating a false reality, a life in which she had rose above the trenches of grief, attended college, the police academy, and went on to join the NYPD in hopes of solving her mother's murder. Rick had been fascinated from the second the doctor had introduced them, allowed him to spend a day in her company.

Integrating himself into her world hadn't been part of his plan, but he wouldn't change it, not now.

There was no single diagnosis, no solution either, but being a natural storyteller himself, Castle had learned that he could help her, gentle the inevitable crash into her true reality that she was often forced to endure. And throughout the last three years, she had been making major improvements.

He became her 'shadow' in her false reality, concocting a series of novels that revolve around the woman Kate Beckett should have been, feeding her fantasies even if it was wrong, and giving her something to feel proud of when the dream world abandoned her.

Three years ago, he had gone searching for a story, and he had found one in her. One he wanted to be a part of.

Her body crumples to the floor, into his lap, and Castle holds her close, cradles her trembling frame against his chest and rocks her back and forth to soothe the frenzied beat of her heart.

" _Rick_ -"

"Your name is Katherine Houghton Beckett," he recites softly into her hair, combing his fingers through the long strands and reeling her back into reality. Like he does, each and every time. "Daughter of Jim and Johanna Beckett, born and raised in New York City. Your - your mother was murdered when you were 19 years old, your father drank himself to death two years later, and you've been here for the last nine and a half."

"No," she moans, sobbing into his neck as the truth reclaims her mind, crushes her soul.

"I've been visiting you for the last three years. We talk almost everyday, I bring you coffee and write novels about you-"

"No, you don't," she cries, clutching the collar of his shirt. "You write them about _her_ , a better me. Not this, never this-"

"And I love you," he continues as if she hasn't spoken, smearing a kiss to the damp corner of her eye. "I love you, Kate. In every story. I love you."

"No," she rasps, burying her face in her hands. "It's all wrong, Castle."

"Stay with me," he whispers, his voice shaking with the plea that rattles its way out of his chest to stain against her forehead. "Kate, you're doing such a good job. We're going to have our movie date tonight," he continues, wiping the tears from her cheeks as her cries begin to soften. "We're going to curl up in your room with my laptop. I brought the snacks, the cocoa, and if Lanie's working the night shift, I'm going to stay until morning, okay?"

He had done it before, fallen asleep in her room, received a soft lecture from Lanie that was meant to curb his late night visits, but only encouraged them. Kate is far from a problematic patient and he's witnessed the leniency she receives from the staff, the way her head nurse is more of a friend than an authority figure in the same nature that the security guards like Ryan and Esposito treated her more like family than an unstable woman in psych ward.

Kate hesitates, but her fingers graze his neck, brushing over the throb of his pulse, calming them both.

"Just – just stay with me in the real world. Stay a little longer. Please."

It's selfish, to ask her for something she has no control over, but throughout the last few months, they've seen improvement, her need for a made up world slowly becoming less vital to her mental stability. But it was a process, a long road to recovery that they had barely stepped foot upon, and he was terrified of regression. Especially when progress meant she was one step closer to beginning to heal, to starting a real life, one that she could share with him if it was what she wanted.

God, it was what he wanted.

"I'm staying," she gets out, her breath trembling its way past her lips, but she lifts her head, meets his eyes and through the darkness, he can see the dull flickers of gold. "I'm here, Rick. Tell me our story again, the real one."

* * *

 _Prompt: Beckett's whole her-mother-was-murdered-so-she-became-a-cop thing was just a hallucination, as she was a patient in a psychiatric hospital, and Castle was just a volunteer, whom played alongside Beckett's hallucination, and fall in love with her._


End file.
